Steering gear for vehicles



April 16, 1935. G, A, GEMMER 1,998,365

STEERING GEAR FOR VEHICLES Filed NOV. 50, 1934 H W 8g 1/3 Patented Apr. 16, 1935 UNITED les ee 4 a s'rnnnmaqnm FOR- trmma (iee 'ae- A, em her watogma it I Application Nqven ber so, 1934, Sgrial No, 155,435

- Glaims-ffl -ntkiom T invention el test s eer n eee e t tor vehicles and. the like; and, particularly to an mprwe lv enti fn'e on ear f; the. term ty e.

T labl sp ce. in met r er a emblie ger 5 un n a s ng e er c nstitute a P ac cal with ta d ham usage er limit on e i e f'the ea n a heueih that y be ueeet g eral th e r mee be m u ted th nerrew p ce be ween the n ine and, the s de f ame or ehess e m m and. his one t o jec s o hi inventie te pte de e eempaet and efitleient .et er ne. ea Whieh. 11% e n d e rel ly'he re hous n that i i y mou ted t use en e reme e item a me er vehicle Y n t is e e e p im y'ebjeet i thi .i vehtieh. 59

pr de ement hee y dnty ea i whie the worm. n agi g element'i eene meted as e ml: .5 s ft or epinqlle tha is su per eqih re ati ely rg be ring She-l tter eeeupy eac a ne' itieh that they leev p p tiened. n aced in r er to be a le te'exert h ir l ibeeit te res t the maximum leadin te rwhieh the part are su e t d infth u e o th a ane he ohieetef his vI. ve ien ie th previ: 'sion e: a s e in s er 0? the worm. type in which he relat ve rra em nt of elem n s is een tha riction een t e worm and the teethehee me he rm is mat riall n ue dZ a d the m chanical advantage oi the gear is, gnbstantially improved, I I V it .iurther hjee e this i ventien e previd a wonn e r here n een eethetwe h he werm and'theteoth enga ing heiwerm enpreh r mates 'tru'e rolling contact over'the mostvgggi portion of the range of operatiqn, Q Another ebJ'ee of th s inveh t9" pr v a s eerin a o turdy construct 'whiehwil lone Peri d 9i ime without requir n repleeem nt e ad us ment 9 the. parts. and whi h wi l ales: e t sim le dee r n a d. eeonomieal'te manu eetuxe g f Qther Qbjee and a a tages Qt hxventien wil become rent from the tol ewihe dete' les deserin ien of the embediment 9f he inVe tiQn ehewn in he aecempan in drawin w erem!" F ure 1 is a seet ena 1 .de elevetieh view e e ste ing g ar eehs ructed in eeeenienee w t th p esent in ention; v a a, I Y .t Figure? is an elevatien View partly inseetieh 1, th lin HA1 F g gure 3 is a diagremillu tretihe 'thexeletieh 9f e ape ed a eeee 9 th p n and th wexh gmnvg with respect to the exie 9f he Ref ri to the skewing, Wh eh er the p31!- PQfies r ill lebratien shows a pr ierred emheqiarthigh heue 9; the prev ew states a evele t r q re m n inventi n; a e hy ntiehe ee i eehm er is indi ated h th um t F;

7, .1 whiehlettei lse eh e the navel 'eeehhe hereinafter 'eee l l-k T e tt ie' reviee; the b lfm e 3 which met be qife aeeze eeei h an e eleee w rm?! uitabl h yee. t theehe t e w th bearing iqiv tmeht e P ide the housingfor taking up'wear or play in the beareeliuetzneht ie in ae ere with eelveh' ienalpxe, aha ew 29 Per? i heh stem 'ihvehtie J A tize tel. tmhnieh '9? tre eh t 5. he n in Fi ur e @1 9 zeteteh y m wed he he. u 111 .e'rehelt hearin 6-. 33 M the e m iezee y ar an e ,herm t Yer airplan eememihe the-e3 5 ef h tee n eel h' geselear yehewn h ieu e al it ns ieteble that the re k; eheh .5 b m ed 3' La euhe ehtie lyhe zeh when in seme it peed net be iiee l "h neh a the i h t 'Whie h k shaft is normal and hipn qpntains the'stearing weu si he a trh tt rh e len at ens w'efthe' eeh ehe twhieh ex end into the heueing 2 1e 'terme'sl ith en emerge ih 1 h lewes! err lee ee. e 1 e Qi eti he d e he the 9!. 99K heath A eehehle-wesher w elin 3. 5 i eneh e l en the e he 5 b tween the h (1 n! hewel! ef h heh h L be n ring} and an'adjgsting screw 9 .A. n a. .v the elpee te ie 913 he h ee ne s e t9 Pes p the ree s aw the h ee e e e? the 9 rhe'hellewesl-eh heedi h re et the xi we'm'fisr ee i t hm i s ed by that the ine 8' e M I p eve? t es ahe'then a itat n h eeeeweto eliminate n eley the met eheitzh vement 1A.. elati ely l n ehei ereh hs I i retetehly ...9 l. 3 i iht e d. he l hle thrust beerin H'- he ehtliri t ieh'h r II we ef amt ef 'thereliler type edepfi 't m tfi e etet en ertheepihel eh'e elw e h to hearing ma he 1?; ?1? e th lie beeh" 4 heee ee 9f the r la i el levee eeer utilizes! in. that? e 9. Ste i si h a "mi e .w a large, n at th epihele be f e size n u h preve t me heht' e? h Spindle Bell @Qd ee eeeetelyie ihe i e n k sheitheee L a The size of the" spugg11e sup e i su l mi and bartigularly its a substantially vertical plane, permits the use of larger size bearings and their spacing, axially of the spindle, inorder to better utilize the individual load carrying capacity of each individual hearing.

The outer rings of bearings II are positioned against suitable spaced-apart shoulders on the inner surface of the hollowed-out head I. Shims I3 may be providedbetween the bearings II and the above-mentioned shoulders to permit axial adjustment of the spindle towardor away from the worm 4. v

The upper end of the spindle I is provided with a tapered surface I2 in the form of atruncated cone. This conical surface engages the tapered surfaces or sides of the groove of theworm'l. --'As the worm is rotated by the steering column I,- the spindle pivots about the axis of and turns the rock shaft 5. The latter is provided with a conven-- tional pitman arm secured toitsiouter end (showndotted in Figure 1), and a suitable -drag link is connected to the pitman arm in accordance with.

contactbetween these two parts. Such rolling contact is obtained when the apex of the conical tooth surface I2 lies on the of rotation of theworm 4. e I

Referring to the diagram shown in Figure 3, it will be noted that the path'of movement of the apexpf the conical surface IZis "the are A of a circle whose center is the point situated on the axis of rock shaft 5. Obviously,the apex of the conicalsurface I2 cannot-lie on the worm axis 0 at all positions of the gear, since'the are A is not a straight line coincident with the straight line worm axisC'; 'By makingfthe distance between the worm axis 0 and therock. shaft axis B relatively great, the curvature of the arc A is reduced and thearc A lies relatively closefto the straight line worm axis C over alimited range D-D or; the total rangeof operation. f-

The rangeof operation most'usedin steering a motor vehicle with this type of agear is arentivelysmall range on both sides of the straight ahead position. In order to provide forv securing approximate true rolling contact throughout this small but .most-used range of operationfjthe straightahead position of the-steering linkage is preferably adjusted so that the axis Dof the spindle I 0 is perpendicularto the worm axis C in that position. i The conical surface of the roller tooth I2 is such that its apex, in this straight ahead position, isslightly above the worm axis C, and also such: that the apexlies on the worm axis C when the spindle axis D is turned to D' a few degrees, for example 2" either side of the straight ahead position D. Throughout this most used range from D to D the are 'A representing the path of movement of said apex is nearly coincident with the worm axis C and therefore approximate true rolling contactis secured in this important 'lfange of operation. The extent of the range D to D depends on the distance between between, wormaxis 1C- and rock shaft'axls B is increased, the arc A approaches the straight line worm. axis- C with a consequent closerapproximation of true rolling contact.

,x The helical groove the worm lat the center of its length preferably has only slight pitch to inima es sure that the gear will be substantially non-reversible in the straight ahead position and in the most used range slightly to either side of the straight ahead position. The non-reversible feature prevents transmission of vibration caused by road shocks and wheel shimmy to the steering wheel, It is also desirable that the pitch of the worm groove increase toward the ends of the worm in order that the motor vehicle wheels may be turned to their extreme positions by; a reasonable movement of the steering wheel. This increased pitch likewise permits the wheels to more easily straighten themselves out after the vehiclehas turned a sharp corner.

Although the construction described above is the preferred-"embodiment of the invention, it

will be apparent that similar results can be obtained with the spindle positioned substantially vertically above the worm while the rock shaft remains below the wormas shown. In this form of the inventionjthe rock shaft is providedwith an arm or arms extending upward around the worm to a hollowedout head in which the spindle would be journalled. The worm in this construction would require to'be convex rather than concave. In this modification, exactly the same approximation of true rolling contact'is obtainable as with the described preferred embodiment. Steering gears constructed in accordance with the present invention are efficient in operation because of the use of an adequately mounted long roller tooth and because of the substantial reduction of friction loss due to the utilization of approximate true rolling contact throughout the most used range of operation. Theease of operation of the gear provides for steering heavy vehicles and trucks with a minimum of effort. By providing that the tooth spindle pivotin avertical' plane containing the steering column axis, it results in a compact and narrow overall housing which is easily mounted on or removed from a vehicle having only a small space between the motor and the sideframe to which the gear is usually fastened. The small'number and simplicityof the parts required for constructingthis steering gear makes it possible to economically manufacture a sturdy device having a long life and unusual ability to withstand the stresses and shocks'to which it is subjected.

This invention also contemplates the use of other types of bearings and connections than those described, as it will be apparent to the skilled mechanic that such variations are possible.

What I claim is: y

1. A steering gear for motorvehicles and the like the combination comprising, a housing for the gear, a steering shaft for operating, the gear, a worm within said housing and secured to said steering shaft, a. rock shaft journalled in said housing and supported therein at right angles to the axis of said worm, a rotatable spindle carried by the rock shaft and journalled' in the inner end thereof with the spindle axis intersecting the axes of said rock shaftand said steering shaft, and adjustable means for axially positioning said rock shaft in said housing to maintain the axis of said spindle in intersecting relation with the axis of said steering shaft, said spindle at oneend having a truncated conical tooth engaging the worm whereby turning of the worm will rotate the'rock shaft, the apex of the cone defining said conical tooth being adjacent and to one side oftthe worm axis when the spindle is perpendicular to said axis, the worm axis and the rock shaft axis being spaced apart a distance such that the conical tooth engages the worm with substantially true rolling contact in the most used sector of engagement.

2. A steering gear for motor vehicles and the like the combination comprising, a housing for the gear, a steering shaft for operating the gear, a worm within said housing and secured to said steering shaft, a rock shaft journalled in said housing and extending therein at right angles to the axis of said worm, a rotatable spindle carried by the rock shaft and journalled in the inner end thereof with the spindle axis intersecting the axes of said rock shaft and said steering shaft and normal to the former, and adjustable means for axially positioning said rock shaft in said housing to maintain the axis of said spindle in intersecting relation with the axis of said steering shaft, said spindle at one end having a truncated conical tooth engaging the worm whereby turning of the worm will rotate the rock shaft, the apex of the conical tooth surface being slightly displaced from the worm axis when the spindle is at right angles to the worm axis, the axis of the rock shaft being spaced from the axis of the worm by a distanceeifective to produce substantially true rolling contact between the truncated conical tooth and the worm over a range of the order of five degrees as these elements respond to turning movements of the steering shaft and in the most used sector of engagement between the spindle tooth and the worm.

3. A steering gear for motor vehicles and the like the combination comprising, a housing for the gear, a steering shaft journalled in said housing for operating the gear, a worm secured to and rotated by said shaft within the housing, a rock shaft journalled in said housing and extending therein at right angles to and spaced from the axis of the worm, an enlarged head member on the end of said rock shaft within the housing, said head being cored out in a direction normal to the rock shaft axis, a roller shaft or spindle element having a conical worm-engaging tooth, the said roller shaft being journalled in roller bearings carried by said head, the said bearings being spaced apart and located at opposite sides of the rock shaft axis, adjustable thrust bearings in contact with said head member for positioning and maintaining said member so that the axis of the said roller shaft intersects the worm axis, and the taper of said worm-engaging tooth and the distance between the worm axis and rock shaft axis being so chosen as to produce substantially true rolling contact between the tooth and the worm over a range of movement of the order of five degrees as these elements respond to turning movements of the steering shaft in the most used sector of engagement between the spindle tooth and the worm.

GEORGE A. GEMMER. 

